1. Field of the Invention
This invention relates to a glass used in an ultrasonic delay line and more particularly, it relates to a glass having a rate of shear wave propagation (V) not exceeding 2.40 Km/sec.
2. Description of the Prior Arts
Heretofore, in order to miniaturize the glass used as delay medium for the ultrasonic delay line, the number of reflections of the wave in the glass delay medium has been increased. However, when the glass delay medium is miniaturized by increasing the number of reflections, spurious signals caused by diffraction of the waves in the delay medium has been disadvantageously increased.
The glass delay medium used in an ultrasonic delay line has been disclosed in U.S. Pat. No. 3,154,425 (Oct. 27, 1964); British Pat. No. 1,118,422 (July 3, 1968); British Pat. No. 1,232,933 (May 26, 1971) and British Pat. No. 1,290,213 (Sept. 20, 1972).
The glass delay medium disclosed in these prior arts has a large rate of shear wave propagation (V) whereby it has been difficult to miniaturize the glass delay medium without increasing the spurious signals.